All four projects in the Program entail a heavy commitment to flow cytometric analysis and cell sorting. We will meet this need by increasing the capacity of the Yale Immunobiology FACS Facility. The only practicable and cost-effective way to do this is to employ a second research specialist, who will extend the working day of the cell sorter from 7.5 to 12 hours, and institute scheduled operation and preventive maintenance for the two analytical flow cytometers.